You wouldn't have been getting $100 if you charged $100 without IAP though, because some of that is going to go to your card processing chain; you'd mostly probably get more than $91 on a $100 charge though.
That depends a lot on how you get paid. Those high CC fees don't exist in Europe, at least not with Visa and MasterCard. There you also have the option to use direct debit, which is much more common for a User than a CC (CCs aren't nearly as wide-spread), with (typically) <50ct fees per transaction.
